this is my data set
RECEIPT_MONTH_YEAR RECEIPT_MONTH
2014-01-01 1
2014-02-01 2
2014-03-01 3
2014-04-01 4
2014-05-01 5
2014-06-01 6
2014-07-01 7
2014-08-01 8
2014-09-01 9
2014-10-01 10
2014-11-01 11
2015-08-01 8
2015-09-01 9
2015-10-01 10
2015-11-01 11
2015-12-01 12
I had set the 'RECEIPT_MONTH_YEAR' as index I need to fill the missing dates and fill na values in the remaining variables
need out like
RECEIPT_MONTH_YEAR RECEIPT_MONTH
2014-01-01 1
2014-02-01 2
2014-03-01 3
2014-04-01 4
2014-05-01 5
2014-06-01 6
2014-07-01 7
2014-08-01 8
2014-09-01 9
2014-10-01 10
2014-11-01 11
2014-12-01 NA
2015-01-01 NA
2015-02-01 NA
2015-03-01 NA
2015-04-01 NA
2015-05-01 NA
2015-06-01 NA
2015-07-01 NA
2015-08-01 8
2015-09-01 9
2015-10-01 10
2015-11-01 11
2015-12-01 12